A method of rebuilding data on a dispersed data storage network comprising a plurality of slice servers and at least one grid access computer, said method performed by said at least one grid access computer, comprising the steps of: i) accessing a data store holding a list of data segment identifiers, said data segment identifiers corresponding to data segments stored by said dispersed data storage network; and ii) for at least one data segment identifiers in said list of data segment identifiers: identifying a list of slice servers storing m data slices associated with said datasegment identifier; said m data slices having been sliced in accordance with an information dispersal algorithm, wherein only 1 of the m stored data slices ae required to reconstruct said data segment and t < m; retrieving status data from each of said slice servers, said status data corresponding to at least t data slices held by said slice servers; characterised by; identifying that at least one data slice holding data associated with said data segment has been compromised based on said status data, wherein the step of identifying comprises: scanning each data segment to identify outdated data slices based on transaction identifiers assigned with each data slice,, and scanning each data segment to compute new respective checksums and comparing each computed new checksum with a stored respective checksum to identify corrupted data slices, wherein said scanning operations are executed on each slice server in parallel, reading t data slices corresponding to said data segment from said slice servers; reconstructing said data segment to obtain a pre-dispersal form of the data segment; re-slicing said reconstructed data segment into a quantity of m data slices according to the information dispersal algorithm; and. replacing at least one new data slice corresponding to said at least one data slice identified as compromised in the relevant slice server. i) accessing a data store holding a list of data segment identifiers, said data segment identifiers corresponding to data segments stored by said dispersed data storage network; and ii) for at least one data segment identifiers in said list of data segment identifiers: identifying a list of slice servers storing m data slices associated with said datasegment identifier; said m data slices having been sliced in accordance with an information dispersal algorithm, wherein only 1 of the m stored data slices ae required to reconstruct said data segment and t < m; retrieving status data from each of said slice servers, said status data corresponding to at least t data slices held by said slice servers; characterised by; identifying that at least one data slice holding data associated with said data segment has been compromised based on said status data, wherein the step of identifying comprises: scanning each data segment to identify outdated data slices based on transaction identifiers assigned with each data slice,, and scanning each data segment to compute new respective checksums and comparing each computed new checksum with a stored respective checksum to identify corrupted data slices, wherein said scanning operations are executed on each slice server in parallel, reading t data slices corresponding to said data segment from said slice servers; reconstructing said data segment to obtain a pre-dispersal form of the data segment; re-slicing said reconstructed data segment into a quantity of m data slices according to the information dispersal algorithm; and. replacing at least one new data slice corresponding to said at least one data slice identified as compromised in the relevant slice server. identifying a list of slice servers storing m data slices associated with said datasegment identifier; said m data slices having been sliced in accordance with an information dispersal algorithm, wherein only 1 of the m stored data slices ae required to reconstruct said data segment and t < m; retrieving status data from each of said slice servers, said status data corresponding to at least t data slices held by said slice servers; characterised by; identifying that at least one data slice holding data associated with said data segment has been compromised based on said status data, wherein the step of identifying comprises: scanning each data segment to identify outdated data slices based on transaction identifiers assigned with each data slice,, and scanning each data segment to compute new respective checksums and comparing each computed new checksum with a stored respective checksum to identify corrupted data slices, wherein said scanning operations are executed on each slice server in parallel, reading t data slices corresponding to said data segment from said slice servers; reconstructing said data segment to obtain a pre-dispersal form of the data segment; re-slicing said reconstructed data segment into a quantity of m data slices according to the information dispersal algorithm; and. replacing at least one new data slice corresponding to said at least one data slice identified as compromised in the relevant slice server.